


What's Past is Prologue

by DelphiPsmith



Category: Harry Potter - J. K. Rowling
Genre: Anti-Muggle Content, Book of Admissions, Chamber of Secrets, Dark Magic, Gen, HP: EWE, Magic and Science, Mathematics, Muggle/Wizard Relations, Post-Hogwarts, Research
Language: English
Status: Completed
Published: 2017-07-23
Updated: 2017-07-23
Packaged: 2018-12-06 02:47:27
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,263
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11591334
Author URL: https://archiveofourown.org/users/DelphiPsmith/pseuds/DelphiPsmith
Summary: Sometimes when you search, you don't like what you find.  Both Severus and Hermione are about to find this out, as a mystery from the past reaches out to touch the present.  (See end of work for original prompt.)Slight warning: Maths involved ;)





	What's Past is Prologue

**Author's Note:**

  * For [KerrAvonsen](https://archiveofourown.org/users/KerrAvonsen/gifts).



> Written for the 2017 [sshg_promptfest](http://sshg-promptfest.livejournal.com/). Slightly AU in that Severus Snape has survived. All dates are historically accurate for both the Muggle and Wizarding world, so far as I have been able to determine; for the few that were/are unknown in the Potterverse, I have chosen dates within the range of canon. Thanks to KerrAvonsen for a wonderful prompt, to my husband (who doesn't "get" SSHG at all but is always happy to help) for the idea that kick-started this story, and to NurseDarry, fastest beta in the west.

~ ~ Part 1: Numbers ~ ~

"...And don't let me catch you down here again, either of you -- if you spent your free time on your homework instead of chasing silly rumors about the Chamber, your Potions marks wouldn't be lower than a flobberworm!"

Chivvied by the biting voice of Professor Snape, two third-years tore blindly round the corner and ran full-on into Professor Hermione Granger, who let out an undignified "Ouf!!" and dropped everything she was carrying. With only a quick "Sorry, miss!" the two were off again.

Muttering under her breath, Hermione knelt to gather up her scattered books and papers. As she reached out a hand for _Muggle Medical Myths: From Leeches to Penicillin_ , a swirl of black robes rounded the corner and a black boot nearly trod on her finger.

The boots stopped short with a muffled oath. "Miss Granger, if you must lurk, can you not find a location where you are less of an obstacle?" 

"If you hadn't chased those students out of Myrtle's toilet so fast they nearly trampled me," she shot back, getting to her feet, "I'd be halfway to my tea by now. And I don't _lurk_ " she added, glancing around to see if she'd missed anything.

"Hmph." Severus picked up a stray scroll of parchment that had rolled over against the wall and glanced at the first line. "'Muggle-Borns: A History'?" He raised an eyebrow. "What is this?"

She snatched it from him and stuffed it under her arm. "My book," she said self-consciously, then added impulsively, "Come and have tea with me in the staff room and I'll tell you about it?"

He looked surprised but, after a brief pause, nodded in agreement. Hermione was rather surprised at herself, in fact. Despite more than a year as Professor of Muggle Studies at Hogwarts, she still occasionally felt intimidated by her senior colleagues, especially Snape, who could skewer with a well-placed glare and flay with a well-chosen word. But really, it was silly to feel that way, after everything they'd been through; maybe tea and a discussion of their respective professional pursuits was one way to get past it.

Ten minutes later they were ensconced in two of the staff room's deep, comfortable leather armchairs, the briskly-burning fire a welcome antidote to the late-November chill. Mugs of tea steamed fragrantly on a table between them, flanking a plate of biscuits.

"So," he prompted after a short silence. "Your book?"

Hermione hesitated. This would be her first book, and she felt rather shy about it. Still, she knew the quality of Snape's work – his papers and studies were excellent and routinely cited by others – so she couldn't ask for a better sounding board. "I'm working on a comprehensive history of Muggle-borns. Not individual people – there are plenty of biographies of famous ones –"

"Such as yourself?" he interjected, hiding a smirk in his tea mug. "What was it called? 'Hermione: Heroine with an M'?"

She groaned and hid her face in her hands. "Merlin, please don't mention that." It had taken her months to live down the horrifically inaccurate biographical sketch produced by Rita Skeeter, in which the woman had pointed out that "hermione" was "heroine" plus an M "which _clearly_ , dear readers, stands for _Muggle-born_ , indicating that Miss Granger was _destined_ for her _very important_ role..." 

"It was rather appalling," Snape conceded. "The only reason she didn't produce something equally execrable on me was that I threatened to adapt the Jelly-Legs Jinx for use on her fingernails."

"You didn't!" she said in delight.

"I did." He rather wished Skeeter had persisted; he would have liked the opportunity to test it. "But we digress."

Hermione indulged for a moment in the pleasing image of Rita Skeeter's poison-green talons limp as spaghetti. "Right, the book. I want to look at the whole phenomenon of Muggle-borns, first in a historical context and then analytically. Have there always been Muggle-borns, or are they a fairly new development? How many are there? Are they always present in the same proportion to the Wizarding world, or does it vary? How common are Muggle-borns in different countries? Is their origin genetic, environmental, or both? Can you predict their occurrence – is there some test, like a Muggle blood test for anaemia? Is there –"

"In short, you want to find out where _you_ came from?" he suggested with a faint smile.

She laughed. "Well, what's wrong with that?" Then, more seriously: "I suppose that's how it started. But the more research I did, the more I realized that nobody has looked into it, not in any serious way. I think even though most of the Wizarding world is fine with Muggle-borns, we're still viewed as not quite a proper subject for serious study."

Snape added some honey to his tea. "Surely there must have been _something_ written on the topic."

"Not really, no. Which is why I already have a publisher," she added with pardonable pride. "Quill & Pica of London."

"Impressive," he nodded. Quill & Pica were known for their rigorous standards. "Where are you getting the historical data?" he went on, genuinely interested. "Muggle-borns as a percent of the population, for example?"

"I've started with the magical schools, looking at the percent of Muggle-borns in each First Year class. I can get the information about Hogwarts easily enough, all the way back to its founding in fact. But the other schools..." She made a face. "Durmstrang doesn't like to share _anything_."

"Back to its founding?" He hardly heard the conclusion of her sentence, so startled was he at her casual words. "Surely you're not planning to use a Time-Turner to go back more than a thousand years!?" 

She toyed briefly with the idea of replying, all wide-eyed innocence, "Of course. Why ever not?" just to see his reaction, then sighed. "Professor—"

"Please, call me Severus," he interrupted. "We are colleagues, after all."

"Severus, then. And as you do admit we're colleagues," she went on with some asperity, "please credit me with more sense than a plimpy. I'm perfectly aware of the instability of time-related magic and the risks of going back that far. Besides, it would take too much effort to collect the data that way. The _Book of Admissions_ is a far simpler method."

Severus felt a combination of relief and chagrin at her answer. Really, he should know her better by now. "I apologize for forgetting that you are the brightest witch of your age," he said with mock humility, waving his wand to reheat both their mugs. "Please, enlighten me. How does the _Book of Admissions_ enter into it?"

"But surely you know? You were headmaster..." She trailed off, flustered, as she remembered that by the end of that terrible May when the incoming First Years' letters would have gone out, Severus had been lying in St. Mungo's fighting for his life as a result of Nagini's attack. "Well, you know the book was created by the four Founders, and that it contains the names of all present and past students at Hogwarts." He nodded and gestured her to continue. "Each May the names of the next intake of First Years appear in the book, with a mark beside each Muggle-born student's name to let the Headmaster or Headmistress know that they'll need to make an extra effort to get their letters to those students, help their parents understand what's happened, and so on."

"That, I did not know." He disliked thinking of his tenure as Headmaster, bracketed as it had been by death and including none of the pleasant duties of the Head, such as sending out their letters to the incoming class of students. "So you have collated this information from the first thousand or so pages of the book? That must have been rather…tedious."

"It would have been." Hermione agreed. "But no, I just figured out how to talk to it."

"You talk to it." He stared at her. "To the Book of Admissions. One of the world's most ancient magical artifacts." Really, she was almost terrifying. "And...it answers you?"

She went a bit pink. "I query the Book for specific pieces of information, which it retrieves for me. I also worked out how to display the results visually – it's hard to interpret that many numbers when they're nothing but a list."

Severus shook his head, his respect for her going up several notches. "Miss Granger –"

"Hermione, please. We are colleagues after all," she reminded him mischievously.

"Hermione, this is remarkable." Magical artifacts were notoriously tricky things; often, just getting one to do what it was meant to was hard enough. To persuade one to do something for which it was not specifically designed was an astonishing feat.

Gleefully, Hermione mentally awarded herself fifty points for having impressed Severus Snape. "I also figured out how to fix the visual representations on parchment so I can keep them for reference," she added smugly. "Here, I'll show you." She leaned down to dig through the pile of books and papers beside her chair. "Drat, I must have left those pages in the Library."

"Never mind, you can show them to me later. Has your analysis turned up anything interesting thus far?" The biscuits were gone, but with a quick word Severus summoned a house-elf and requested something a bit more substantial. It was a mark of Hermione's focus on their conversation that she didn't even frown at him for inconveniencing an elf. 

"Two things, actually, though I don't know yet what they mean, or if what I've found is unique to Hogwarts or occurs at all the Magical schools." Absently she took a sausage roll from the platter that had appeared at her elbow. "First, the percentage of Muggle-borns in each incoming year – at Hogwarts, at least – is amazingly consistent. It's held steady between seventeen and twenty-three percent, ever since the school was founded in 933."

"No deviations?"

"Only four. In 1357, shortly after the school was founded. Then in 1929, 1968, and most recently 2006. In each of these years the number of Muggle-born First Years at Hogwarts plummets to around four or five percent. Sometimes the lower rate holds for a few years, sometimes for a couple of decades, then it goes back up to normal. But otherwise no, no deviations over more than a thousand years."

Severus took a bite of his cheese sandwich. "If one wished to find something that affects the number of First Years, would it not make sense to look for a cause eleven years previously, the year those students would have been born? Which would be, let me see, 1346, 1918, 1957, and 1995."

"Yes, I thought of that, too." Hermione felt a glow of pleasure. Harry and Ron had tried manfully to appear interested when she'd talked this through with them the week before, but they'd clearly been bored stiff. How satisfying to talk to someone who thought logically! "When I started looking at those dates I thought I'd found something, but it didn't pan out."

"What was it?"

"Epidemics. Fewer people, fewer children. And Muggles are more susceptible to illness than Wizardkind, so an epidemic would reduce the number of Muggle-borns more than the number of Purebloods or Half-bloods."

"Logical. You are thinking of Dragon-pox, for example? Or no," he corrected himself, "this is about Muggle-borns, so—"

"A Muggle epidemic, exactly!" she confirmed. "And start dates for three of the four drops do correlate with three of the most deadly Muggle epidemics ever. Starting in 1346, the Black Death killed somewhere between seventy-five and 200 million people. Spanish Flu killed between twenty and fifty million people in 1918. Asian Flu in 1957, a lot fewer, only two million. But there's nothing in 1995 that would correspond to the 2006 drop."

"Hm, yes, that is a problem." Even in the Wizarding world, the deaths of millions of Muggles did not go unnoticed. Had there been anything remotely on that scale in 2006, it would have been news in both worlds.

"More to the point," she went on, "if epidemics were the cause of the drop in Muggle-borns, then the return to normal rates should correspond to the end of the epidemic. Only eleven years later, of course."

"And they don't," he guessed.

She shook her head, annoyance plain on her face. "The first one does – the Black Death lasted four years, from 1346-1350, and there were fewer Muggle-borns in First Year classes from 1357 to 1361. But the Spanish Flu lasted only two years while the drop in Muggle-borns lasted nearly thirty... Hang on, I have my notes here somewhere..." She bent down and dug through her pile again. "Ha!" she said triumphantly, extracting a scrap of parchment and handing it to Severus. "See for yourself."

Severus smoothed the parchment and scanned its contents, reflecting briefly how often he had seen the same writing on Potions assignments. Even then there had been an unusual confidence in its energetic scrawl.

_Black Death: 1346-1350  
Lower % of Muggle-borns: 1357-1361_

_Spanish Flu: 1918-1920  
Lower % of Muggle-borns: 1929-1956_

_Asian Flu: 1957-1958  
Lower % of Muggle-borns: 1968-1992_

_???? : 1995-?  
Lower % of Muggle-borns: 2006-2009_

"The pattern is certainly suggestive," he admitted, laying the parchment aside. "Numbers from other magical schools would, of course, be helpful."

She made an annoyed face. "I know. But it turns out that not all Wizarding schools keep the same type of records, and those that do aren't exactly happy to share, for some reason. I'm hoping for the best though." She sat back in her chair and sighed. "But enough about my work. What about yours? Do you have a current research project?"

"Yes," he said, after a moment's hesitation. "I too am going back to Hogwarts' founding, but unlike you I am staying there."

"That sounds mysterious. May I have another hint?"

He refilled his mug and, when she nodded at his questioning glance, hers. "I am interested in Salazar Slytherin and the Chamber of Secrets."

"Ah," she said, suppressing the queasiness that memories of her encounter with the basilisk still engendered. "Which is why you were in Moaning Myrtle's bathroom, chasing those third-years out."

He grimaced. "Minerva's decision to make the Chamber freely accessible to the entire student body was, on the whole, a good one. It reduces the dark mystique associated with the place, and with Salazar himself, which can only benefit Slytherin House. However, she perhaps did not account for the irrepressible need of the young for excitement." 

Hermione snorted. "I don't know about 'the young' in general, but I can tell you I could have done with a lot less excitement as a student. What was it you said to them? Something about a rumour?"

"There is a rumour circulating amongst the students that the Chamber is not entirely...dormant. That despite the death of the basilisk, something magical – actively magical – still lurks there, detectible as a hum or vibration or tingle or some such nonsense." He waved the fingers of one hand dismissively. "Ridiculous, of course, but there are always a few dunderheads who will persist in believing such tales." 

She toed off her shoes and curled her feet under her. "What about you? Did you sense anything?" 

He started to speak, then appeared to change his mind. "Nothing. Although the statue does, I admit, induce a certain amount of...unease, with its blank eyes and gaping mouth."

Hermione watched him narrowly. If anyone could sense Dark Magic, it would be this man who had seen more of it, and more closely, than any of them. Perhaps there was more here than he was ready to admit. "If there's nothing there, what's your interest in it?"

"The Chamber of Secrets was a truly astounding achievement," he said simply, his eyes on the flickering fire. "I think we underestimate the sheer power required to accomplish it. All four Founders were very potent Wizards, of course, but what Salazar did was unprecedented then and has not been matched since. Consider: he was able not only to create an enormous room but insert it into Hogwarts itself, a structure whose every stone is permeated with defensive magic. Hogwarts was created by all four of the Founders, and yet he did this without the other three realizing it. When rumor of what he had done reached them, they were unable to even locate the room, let alone determine the nature of the threat it posed."

"I see what you mean," Hermione mused. "None of those things should have been possible."

"Indeed," Severus agreed. "He also tamed a basilisk, King of Serpents – even Herpo the Foul, who hatched the first one of all, never managed such a feat. Not only that, he found a way to preserve it, alive and vital, and mask its presence for a _thousand years_. The fact that a mere second-year student managed to find the Chamber and defeat the basilisk, even granted that he was the Chosen One" – this with a tinge of mockery – "and had the assistance of Dumbledore's phoenix and Gryffindor's sword, masks the magnitude of Salazar's achievement. Destruction is, after all, much easier than creation."

"I never really thought about it," Hermione admitted. "Taken altogether, it is quite impressive."

"Salazar has attracted his fair share of critics, and deservedly so. But there is also much of which Slytherin House can be proud," Severus said, his tone half-gratified, half-bitter. 

"So you're curious how he did it?" Hermione asked hesitantly, after a long moment.

"How, certainly. Where does such immense power come from? But also why."

Hermione was taken aback. "Well, we know why, don't we? He wanted a place to teach his students the Dark Arts, as well as a home for the basilisk, a weapon to help his heir purge Hogwarts of Muggle-borns."

"Certainly those were two of his reasons," Severus acknowledged. "But what if there was more to it than that – other plans, other weapons? Slytherins are notorious for having secrets within plots within schemes. We never have just one reason for doing something."

~ ~ Part 2: Power ~ ~

_Dear Godfather –_

_I have, as you requested, searched the library here at Malfoy Manor for information on Salazar Slytherin and the Chamber of Secrets. (I hope our little collection of Salazariana remains known only to yourself; I would hate for ~~those idiots at~~ the Ministry to seize and destroy such an irreplaceable piece of history!) Unfortunately I can add little to what you and I, and many others, already know: Salazar created the Chamber shortly before he was ousted from Hogwarts in 1346 for his ~~entirely understandable~~ preference for Purebloods. In a letter to a Malfoy ancestor, written not long after his departure from the school, Salazar congratulates himself on having 'successfully activated the Devourer, before the Muggle-lovers drove me out.' Muggle-lovers no doubt refers to Godric Gryffindor, Rowena Ravenclaw, and Helga Hufflepuff, and I assume the Devourer is – was – the basilisk._

_Interestingly, an entry in the family journals, which go back several centuries, reads 'This nyght died Salazar Slytherin, mightie in our Pure Bloode Cause. Foryeten be hee naever.' The entry is dated 1350, so he would have been 447 years old – a remarkably advanced age, which Father believes was due to his tremendous magical strength. So far as I know, the date of his death isn't recorded elsewhere, perhaps because Slytherin has never appeared on a Chocolate Frog card ~~due to the gross prejudice of some people~~._

_I hope this is useful to you. Mother sends her love._

_Draco Malfoy_

Standing in the dank shadows of the Chamber of Secrets, Severus re-read the letter from Draco, then tucked it into his sleeve. The silence was absolute, except for the regular drip, drip, drip that echoed from the slick green walls as water trickled from the statue's chin. Although he had told Hermione he sensed nothing, he was not as confident as his words had suggested. 

He thought of Salazar Slytherin: his unyielding pride, his subtle mind, his conviction of his own superiority. The walls of the Chamber seemed to press outwards, resisting the surrounding force of the castle in which it was embedded as Salazar had resisted his three fellow Founders. An alienness pervaded the room: egg of a cuckoo left for an unsuspecting host, egg of a chicken hatched beneath a toad. Even after so many centuries and the loss of its serpent denizen, the throb of power was palpable.

Perhaps the rumor was true. Perhaps a "live wire," as the Muggles would say, remained. He could not escape the feeling that the Chamber was not dead, only waiting.

He paced the stone floor, hands clasped behind his back, then paused and gazed up at the blind eyes of the statue, the open mouth. The mouth disturbed him for some reason. Not closed, firm and resolute as one would expect of a wizard of Salazar's caliber, but gaping wide. Why had he chosen to portray himself so? Salazar as Parselmouth, therefore a symbolic passage for the King of Serpents who could only be controlled by Parseltongue? Curious that Salazar would refer to the basilisk as a Devourer, since it did not eat but petrified its victims. It could be – but no, that was a myth. Perhaps the mouth was open in a shout of defiance. Perhaps it signified his hunger for power. It could have been all of those, and more besides. After all, Slytherins never had just one reason for doing something, as he had told Hermione. All Slytherins were devious, and generally it served them well – better, sometimes, than outright power. Salazar, of course, had had both: an intricate mind and unmatched power.

Was it unmatched, though? Severus stared at the blank face, struck by a question that had never occurred to him before. Had the enormous strength evident in this room truly been an anomaly, or had there perhaps been other incredibly powerful wizards that remained unambitious and therefore unknown? How often did wizards like Slytherin, or Grindelwald, or Dumbledore, or – yes – even Harry Potter come along? Everyone in Dumbledore's Army – not just Potter – had managed to conjure a Patronus, for example. Strange when one thought about it, a group of relative children mastering such advanced magic. Had their class been unusually strong in general? If so, why?

It occurred to him that Hermione had begun her research with data she obtained from the _Book of Admissions_. Might it hold an answer, or at least the beginnings of an answer, to his own curiosity about the relative power of witches and wizards over time?

Twenty minutes later Severus was outside Minerva's office, in his hand a list of the query phrases Hermione had devised. She'd been perfectly willing to share them, though he'd had to be almost rude in brushing away her questions.

"Severus," Minerva said, courteous as ever, when he entered. Her eyes fell on the sheet of parchment he held. "Ah," she went on with a smile. "I see Miss Granger has shared with your her discoveries about the _Liber Admissionem_."

Severus cleared his throat. "Yes, quite remarkable. Would you mind if I...?"

Minerva gestured to him to enter. "By all means, Severus. I'm just off to luncheon with Pomona and Poppy. Please, make yourself at home." She waved her wand to lift the glass case protecting the Book, then swept out, leaving him alone.

The list of commands Hermione had given him progressed from a single two-word phrase at the top ("Quid discipulorum?") to a fiendishly complicated sentence at the bottom, complete with notations about wand movements and various inflection markings. Still, how hard could it be? He chose a phrase from the middle of the list at random and spoke it aloud.

The book emitted a puff of sparks, then a thick cloud of purple issued forth. The cloud began to swirl about his head, numbers and lines forming and dissolving, slowly at first then faster and faster until he grew dizzy attempting to bat them away. "Finite incantatem!" he finally roared. The cloud slowed to halt and gradually dissipated. The book's pages ruffled softly; he could have sworn it was laughing at him. Perhaps he ought to start with something simpler.

An hour later, gazing at the shimmering web of multicolored lines, numbers and curves resulting from his latest query hanging in the air before him, Severus was more than a little in awe of Hermione's achievement. He had always appreciated power, whether magical or intellectual, and here was a perfect blend of both – and lovely to look at, as well. Not only could Hermione's commands be used to retrieve and display any conceivable piece of information, with the proper commands the various components could be manipulated to sum or average, expand or shrink, zoom in for more detail and out for less detail, chart one type of information against another, or even overlay one or more sets of information for comparison. The possibilities were endless, and the more complicated the query the more beautiful the results, making each display a unique work of art. 

Truly, this was magic.

At last, with a sigh, he dismissed his latest visualization, a complex web showing hair color overlaid on blood status and gender (all six categories), mapped against time and date of birth. August 11 through 22, he noted idly, seemed to produce an unusual number of Pureblood redheads.

He referred once more to Hermione's list, thought for a moment about how to correctly phrase his query, then moved his wand in a graceful series of movements and spoke carefully aloud.

"Omnes discipulos, quisque annos singulos, mediocris magica potentia magnitudinis; potentia ad sinistram, annorum inferius. Ab initio," he added hastily.

A greenish mist flowed smoothly out of the book. It merged and divided, swirled and straightened, condensed and brightened until it resolved into a single undulating horizontal line, like a strand of emerald fire. A vertical axis marked from zero to 100 in gradations of ten floated to its left, and a horizontal one marked in ten-year increments from 933 to 2017 hung in the air below it. For most of its length the line wavered within one or two ticks of the 50 mark, but there were three...no, four clusters where the line reached a higher plateau, indicating exceptionally strong magical power in those years. 

"Fascinating," Severus murmured. As he bent closer to examine the dates associated with the first cluster he heard footsteps behind him and then Hermione's amused voice. 

"You've got it upside down."

He turned in surprise, then back to his visualization. "Upside down? What do you mean?"

She gestured towards the display he had conjured. "That's my Muggle-born data. But you've got it upside down, so the lower rates of Muggle-borns look like spikes." She moved in for a closer view, then frowned. "No, it isn't my data. What is this?"

"Relative magical strength of First Years," he said slowly. "Over time."

She tapped her wand against her chin. "Expand it. Let me see – no, wait." With a few practiced motions and a muttered phrase, she conjured her own visualization and overlaid it on his as a line of glowing blue.

The two lines were exact mirror images of one another, flipped vertically.

Without speaking, Hermione magnified the glowing diagram until they could see individual dates: 1357-1361, 1929-1956, 1968-1992, 2006-2009. The two patterns were a precise match, even to the years they began and ended.

"I don't understand," she mused. "What would affect both the number of Muggle-borns in a class as well as its magical strength?"

"Could it be that Muggle-borns in general are less powerful, so when there are more of them, they bring the average down?"

Hermione gave him a withering look, but instead of arguing as she obviously wanted to, she dismissed their joint display with a quick _finite incantatem_ and launched a series of complicated queries, pulling one shimmering web after another out of the _Book of Admissions_ and as rapidly dismissing them. Although Severus was not nearly as fluent as Hermione in this new skill, he was able to follow along closely enough that, by the time she was done, he could tell the answer for himself.

He shook his head, genuinely puzzled. "It makes no sense. Muggle-borns are no weaker or stronger than their fellow Pureblood or Half-blood students. And yet every time the number of Muggle-borns in a given class plummets, that class shows a markedly higher average strength." He glanced at Hermione. "What have we found?"

"I don't know," she said. "It's almost as if..." She broke off, a strange look on her face.

"As if what?" 

"As if," she said slowly, "having fewer Muggle-born students causes magical power to become more concentrated."

"Explain."

"Well, usually there would be eighteen or twenty Muggle-borns in a class, as you can see, but here, during these periods" —she gestured towards the dips— "there are only five or six. But the _power_ those non-existent students represent—"

Severus frowned. "—is still there, distributed amongst the existing students. Meaning that each student is considerably stronger than he or she would have been otherwise. As if that excess power was somehow transferred to them." 

"Or taken from the others," she added uneasily. "But how would that happen? It's not like there's a fixed amount of magical power floating about in the aether that gets divvied up among newborn witches or wizards. Is there?"

He smiled briefly. "No, that much we do know about magic. One witch or wizard being born stronger doesn't automatically mean someone else is born weaker, as if we leeched off one another. It must be some natural—" He broke off at Hermione's gasp. Her face had gone white as ashes. "What is it?" he said quickly. 

"Oh, god." She pressed a hand to her mouth. "Severus..."

He took her by the shoulders, disturbed by her obvious distress. "Hermione, what's wrong? Are you ill?"

"What if one witch or wizard being stronger _did_ make another one weaker?" Her eyes were wide with shock at the idea.

"You're not making sense," he growled. "Witches and wizards are born with their power. It's innate, not acquired through some kind of magical vampirism."

She shook her head in mute denial. "Think about it, Severus. It would explain everything. There are fewer Muggle-borns during those years because the magical potential of most of them, the ones who _should_ have been there, was... I don't know, consumed, drawn off somehow by the other witches and wizards born that year. Some were able to withstand it, to retain their magical heritage, but most of them, the weaker ones, weren't. Instead of Muggle-borns, they became...just Muggles."

He gave an incredulous laugh. "Don't be ridiculous, Hermione. It's common knowledge that the magical strength of infant witches and wizards is somewhat malleable during their first year of life, but certainly an infant would never be capable of devouring someone else's magic. Even supposing such a power existed, how could an untrained infant control it enough to target only Muggle-borns?"

He watched the color began to come back into her face. "That's true. Of course." She took a deep breath. "I'm sorry, I'm not thinking straight. It just..." She shook her head. "It fits the data, but you're right, it doesn't make any sense."

"I think we need to expand our research beyond Hogwarts," he said, relieved that his logic had convinced her. "Perhaps the key lies there."

~ ~ Part 3: Time ~ ~

"I think we need to look at the ends," Hermione said. "And maybe the durations." She was lying on the floor in Severus' rooms, the end of a quill between her teeth, surrounded by parchment covered with scribbled notes and captured visualizations.

She and Severus had spent the past week attempting to pry information out of the other Wizarding schools in an attempt to determine whether the pattern they'd seen with Hogwarts students was reflected in other student bodies. They had been more successful than she had hoped – Severus had even been able to persuade the Heads of Durmstrang and Koldovstoretz to respond, although the latter had delivered theirs in the form of a viciously fanged volume enchanted to believe itself a dragon, which required several owls to Charlie Weasley before they were able to open it.

Fortunately, Hermione's ability to talk to the _Book of Admissions_ (which she had dubbed Magicis Selectivam Quaestionem ab Libro) proved to be easily adaptable to other volumes, though the lengthy narrative passages in the Beauxbatons records rather threw things off. Numbers were apparently easier than language to extract and manipulate, a fact which pleased Hermione and irritated Severus.

All of this additional research, however, had failed to advance their knowledge: At all other schools, Muggle-born students hovered consistently at around 20%, and the average magical strength of a class never deviated more than three or four points. There were no spikes in power, and no dips in Muggle-borns. Hogwarts was, apparently, unique.

"Why so?" Severus inquired, looking up from the table where he was skimming obscure volumes of magical history in a (so far vain) quest for clues.

"Because the beginnings aren't getting us anywhere."

"You still believe there is some connection with Muggle epidemics?" he asked, laying in a quill to mark his place and closing the book.

She rolled over and sat up, resting her elbows on her knees. "Yes, I do. But there's nothing like that in 1995, eleven years before the 2006-2009 dip. Or spike, depending on which set of data you're looking at. I can't explain that. So, let's look at the ends. There's clearly no link to Muggle epidemics there." 

"The dates of these anomalous periods are 1357-1361, 1929-1956, 1968-1992, and 2006-2009," he recited. By now they both had the four date ranges memorized. "The dates eleven years prior to the end of each period, when the last of the unusual First Year classes would have been born, are 1350, 1945, 1981, and 1998."

Even as the last syllable left his lips, Hermione could see the dawning excitement she felt reflected in Severus' face. Three of those dates were known to every child and adult in the Wizarding world. "Voldemort's two defeats," she said. "In 1981 and 1998."

"And Grindelwald's fall and imprisonment in Nurmengard, in 1945," Severus added thoughtfully.

"Severus, that's three out of four linked to the fall or defeat of major Dark Wizards!" she said, then frowned. "But I can't think of anything in 1350."

"I can," said Severus reluctantly. Although it irked him to suggest yet another black mark against his House's founder, he could not withhold potentially valuable information. "The death of Salazar Slytherin."

"That would certainly count as a fall," she agreed, then narrowed her eyes. "But the date of Slytherin's death has always been a mystery. It isn't documented anywhere. How do you know it?"

He shrugged. "It doesn't matter," he said, unwilling to bring trouble on Lucius and Draco. The Malfoys had enough problems without the Ministry descending and trying to confiscate their library. "But I am certain the date is correct." 

She rose and came to sit across the table from him. "Severus, this might be it," she said excitedly. "Forget the epidemics, maybe I was wrong about that. If the ends of these periods are correlated with Dark Wizard activity, maybe the beginnings are too! Salazar left Hogwarts in 1346, didn't he? Which means he built the Chamber that same year, just before he left – and that's eleven years before the first one began!"

Severus nodded, catching some of her enthusiasm. "And Voldemort's second rise began in 1995, when he regained physical form. There is our second match."

"The other two dates are 1918 and 1957," she went on. "The first one must have been something Grindelwald did, since it's paired with his fall in 1945. The second must be something to do with Voldemort, since it's paired with _his_ fall in 1981."

"Tom Riddle disappeared for ten years, shortly before 1957," he said. "It is reasonable to conclude that he did something significant during that time that launched his rise to power, since when he returned he had essentially become Lord Voldemort."

"Do you know of anything in particular? Did he ever mention anything?"

"No. But..." Suddenly a memory surfaced: the summer of 1997, a terrified woman suspended above a table. "Professor Burbage. The night she died, Voldemort referred to her as a fortieth anniversary gift to himself. None of us understood what he meant." He shuddered.

Hermione laid a gentle hand on his arm. "Severus, don't torment yourself," she said softly, then went on briskly. "The only remaining question, then, is Grindelwald in 1918." She twiddled a quill between her fingers, frowning and tapping the parchment rhythmically. "But Severus, we've established that the anomalies only show up here, at Hogwarts. Salazar and Voldemort, it makes sense that whatever they were doing would be connected to Hogwarts – one was a Founder, the other was obsessed with the school, to the point that he made a Horcrux out of Ravenclaw's diadem. But Grindelwald, he went to Durmstrang. He never even visited Hogwarts, did he?"

"I cannot say." Severus rose from the table. "But we know someone who can. Come."

~~

"I assume at some point in the near future you two will tell me what you are up to," Minerva said with a severe look, following Hermione's hurried explanation that they needed just a few minutes with Dumbledore's portrait and would she mind very much, it really was important. She glanced at Severus. "I thought you at least, were past the days of keeping secrets, Severus."

"We are simply hoping that the Headmaster can help us with some historical information," he replied smoothly. "All in the past, Minerva. Along with my misdeeds, and your own," he added with a smirk.

"Hmph," she said, flushing faintly and patting her hair. "Well, I shall leave you to it then, but please don't be too long. Professor Flitwick and I have an appointment in fifteen minutes to discuss the fourth-year Charms curriculum."

The door closed behind her as Severus and Hermione approached the slumbering portrait of Albus Dumbledore. A gentle snore rose from the ancient figure.

"Excuse me, sir," Hermione said, tapping gently on the frame. 

The snore changed its rhythm, but the sleeper did not wake.

"Please, sir. We need to ask you something, about...about Grindelwald."

The snores ceased abruptly, then resumed as the Headmaster burrowed his chin deeper into his beard, his eyes tight shut.

"Albus," Severus said firmly. "Such childishness is beneath you. We need your assistance."

Bright blue eyes opened behind half-moon glasses, and the portrait sighed. "Severus. And Miss Granger, how nice to see you. How may I help you?"

"We need to know if Grindelwald was ever here," she said. "At Hogwarts. Maybe before he... Maybe when you were students?"

Dumbledore gazed at her for a long moment. "It is not good to dwell on the past, Miss Granger," he said finally. "Surely an old man should be permitted to put it behind him."

"I know, sir, and if there were any other way to find out what we need to know, we wouldn't bother you. Honestly, sir."

Dumbledore rose from the painted chair and began to pace from one side of the frame to the other, hands clasped behind him. "No, Gellert never came here as a student," he said quietly. "Nor did I visit Durmstrang. The two schools have a history of rivalry, and even then Durmstrang had, shall we say, a Dark reputation. But he did come to Hogwarts once, in 1918."

Severus and Hermione exchanged glances.

"He came in secret, of course," Dumbledore continued heavily, "since he had recently acquired the Elder Wand and most of the Wizarding world was hunting him. He wished to try one last time to persuade me to his point of view. Nearly twenty years had passed since our falling-out and Ariana's death, and he hoped that the time apart would have mellowed my feelings."

"Was he here long, sir?" "What did he say?" Hermione and Severus spoke at the same time.

"When I made it clear to him that all was, and must forever be, over between us, and that I would oppose him in any way possible, he was furious. Angrier, perhaps, than he had been when we fought twenty years before. He raged at what he called my 'obsession with Mudbloods.' In the end, he swore that he would make Hogwarts itself devour all my hopes. Had I been less harsh..." The old wizard shook his head regretfully. "It was shortly afterwards that his campaign of terror began."

Hermione shot a sharp look at Severus, whose face betrayed that something in Dumbledore's words had struck home.

"Thank you, sir," she said firmly.

~ ~ Part 4: Cause and Effect ~ ~

Back in Severus' quarters, Hermione rounded on him instantly, as he had known she would.

"Something he said, it caught your attention. What was it?"

"In a moment." From the mass of books and papers on the table, he retrieved the piece of parchment that held their master list of dates and events (it had been folded and unfolded, passed back and forth, words scribbled and crossed out innumerable times, and was looking rather bedraggled). He leaned across the table to pick up a quill, added a few lines, then shoved it into the center of the table.

"Tell me what you see," he said, his voice taking on its familiar didactic tone.

She started to argue, then bit it back and looked at the parchment:

_Fewer Muggle-borns/Stronger students: 1357-1361_  
11 years prior to start: 1346, Black Death  
Salazar builds Chamber of Secrets  
11 years prior to end: 1350, Salazar's death 

_Fewer Muggle-borns/Stronger students: 1929-1956_  
11 years prior to start: 1918, Spanish Flu  
Grindelwald visits Hogwarts; his rise begins  
11 years prior to end: 1945, Grindelwald's fall and imprisonment 

_Fewer Muggle-borns/Stronger students: 1968-1992_  
11 years prior to start: 1957, Asian Flu  
Voldemort commits some unknown action; first rise begins  
11 years prior to end: 1981, Voldemort's first defeat 

_Fewer Muggle-borns/Stronger students: 2006-2009_  
11 years prior to start: 1995, ???  
Voldemort regains his body; second rise begins  
11 years prior to end: 1998, Voldemort's death 

"Four periods of heightened activity by a powerful Dark Wizard," she said slowly, feeling her way and alert for anything she might have missed. "In three cases, the beginning of this period is correlated with a Muggle epidemic." She glanced up. "I thought – is that important after all?"

"I fear it may be. Go on."

She sank into one of the chairs as she returned her attention to the parchment. "The beginning of each period is correlated eleven years later with First Year classes at Hogwarts having very few Muggle-borns, but a far higher average magical strength. In each case, this low Muggle-born/high power situation persists for a different number of years. But in all four cases, the fall of the Dark Wizard involved is correlated eleven years later with a return to normal in both the number of Muggle-borns and the average magical power of First Year classes."

Snow spattered against the window, and Severus went to place another log on the fire. "Four eras of enormous power exerted by Dark Wizards – Salazar, Grindelwald, Voldemort – all of whom particularly hated and despised Muggles and Muggle-borns."

"Matching four eras of very few Muggle-borns at all." A chill ran up her spine. Suddenly she was unsure she wanted to follow the chain of logic to its end.

"Grindelwald told Dumbledore that Hogwarts would 'devour' his hopes. I believe he chose that word deliberately." Severus went to his desk, took Draco's letter from a drawer, and handed it to her. 

She read, frowning in concentration, then looked up. "'I have activated the Devourer'," she said quietly. "This means something to you."

"I had thought it was merely a myth, but now..." He looked away. "If anyone would have known, and been capable of such a deed, it would have been Salazar Slytherin."

"Tell me, Severus."

If only the Sorting Hat had shouted _Gryffindor!_ when placed on his head, rendering him utterly unconnected in any way with the horror he was about to name. He took a deep breath. "I believe Salazar discovered how to create a _Devoratrix Magicae_ ," he said. "A Devourer of Magic. A way to consume the magic of others. And that both Grindelwald and Voldemort used Salazar's creation in their turn."

"Consume the magic of others?" Hermione repeated faintly, nauseous at the very idea of such an obscenity. 

Severus fetched a bottle of Old Ogden's and two glasses from a cupboard. He sloshed a generous measure into each and handed one to Hermione. "Here. I think we'll need something stronger than tea for this conversation." 

She thought of vampires, of Dementors. Would it be worse to lose your blood, your soul, or the magic that was as much a part of you as either? "This Devourer. Is it a spell? Or an artifact?"

He sat down across from her. "Both, according to legend. An artifact imbued with certain very specific characteristics must be created. The process is slow and exacting, but does not require a great deal of magical strength. The spell to activate it, however – opening the mouth, as it were, to begin the consumption of others' magic – requires enormous amounts of life-force, far more than any single witch or wizard could supply alone."

"But the caster cannot draw on the magic of others _until_ the Devourer is activated. So how...?"

"Life-force, I said. Not magic." Merlin, how he hated that he even knew such things. "It is...possible to pull the life-force from other living creatures. Naturally, the victims are severely weakened and easy prey for illness." He hesitated, but before he could go on she had made the connection.

"My god," she whispered, horrified. "The epidemics. Millions of deaths, over and over again, all to feed Pureblood ambitions." She shook her head. "How could anyone be so callous, so cold?"

"Hating Muggles as they did, all three of them must have relished the thought that choosing this method of enhancing their own power would also result in the deaths of untold numbers of those they despised. Once the mouth of the Devourer is open, so long as it remains open, the witch or wizard who controls it can feed on the magic of others at will."

She took a swallow of the whisky, then gazed steadily at him, her face pale and set. "And who better to be fodder for this Devourer than Muggle-borns?" she asked quietly.

He would have given anything not to be a Slytherin at that moment. "Nothing in the legends suggests that the Devourer can be targeted to a particular group," he said. "But yes, knowing what we do of Salazar Slytherin, he may have found a way. Indeed, the evidence you and I have found suggests that he did."

"I was right, then, in a way," she mourned. "All those potential witches and wizards, born into Muggle families -- someone _did_ steal their power."

He took her hand. "Hermione, this is all in the past," he reminded her gently. Which was mostly true, and with luck he could turn her thoughts away before she followed the final link in the chain. The thought of what it might do to her was not a pleasant one.

"I know. But I can't help but think... All their magic, taken from them. An entire future, snatched away. They never became witches or wizards at all." Anguished brown eyes met his. "And they never even knew what they'd missed." She gave a sniff. "Sorry."

"Don't be. Here." He proffered a handkerchief, which she accepted without looking at him.

"So," Hermione said after a moment, in something close to her normal voice. "I suppose the Devourer's mouth closes when the witch or wizard who opened it dies, since everything was back to normal eleven years after Salazar's death."

"And eleven years after Harry killed Voldemort during the Battle of Hogwarts," he confirmed.

"But Grindelwald was imprisoned in 1945, not killed," she pointed out. "So there must be another way to close it."

"The walls of Nurmengard are powerful magical dampeners," Severus reminded her. "When Grindelwald was imprisoned there, not only was he unable to use the Devourer to consume the magic of others, his magic was completely neutralized. With nothing to hold it open, the mouth would have fallen closed."

She nodded. "Yes, all the dates fit. Voldemort reopened it in 1957 – the Asian Flu epidemic. And when he was defeated the first time, when the Killing Curse rebounded on him, it fell closed."

"Not closed, I think. Only dormant. Voldemort certainly ceased to feed on the magic of potential Muggle-borns, as we know because the proportion of Muggle-born students returned to normal eleven years later, in 1992. But he was not dead, nor was he imprisoned behind magical barriers, and bits of him remained, in the Horcruxes."

"So there might have been enough of his magic still present to hold the mouth open?"

"Yes. We cannot know for certain, of course, but when he began to feed again in 1995, upon regaining corporeal form—"

"My missing epidemic!" Hermione clapped her hands.

"Precisely." He could not help but smile at her satisfaction in being proven right after all.

She laughed. "It's like the dog that didn't bark."

Her words left him entirely fogged. "The dog...?"

"Sherlock Holmes. A Muggle detective, in a case about a stolen racehorse." She waved a hand. "Never mind. But Severus," Her face grew sober again. "These Dark Wizards – Salazar, Grindelwald, Voldemort – they didn't just steal the power of...well, people like me. Muggle-borns. They _gorged_ on it. They couldn't possibly have used it all."

He shrugged, feigning a nonchalance he didn't feel. "Who knows?"

But she was too sharp for him. "One wizard, channeling the magic of thirteen, fourteen, fifteen infant Muggle-borns every year? Granted the Chamber of Secrets and the other things they were doing took an enormous amount of magical power, still..." Her voice trailed off. "Overflow."

And there it was, the thing he had not wanted her to see. He could only watch, helplessly, as she fit the final, fatal piece into place. 

"That's it, isn't it? The reason First Years born during those periods had more magical strength. Overflow from the Devourer gave it to them." Her horror-struck gaze met his, reading confirmation there. She rose from the table so quickly that her chair tipped over. "Oh god, Severus."

He rose swiftly and came around the table to put an arm around her. "Hermione, please." He'd grown accustomed to seeing self-hatred in the eyes he saw in the mirror. He wasn't sure he could bear seeing it in hers. 

She shook him off. "Don't you understand? I was born during one of those periods." How could she accept sympathy for being complicit in a crime, however unwittingly? "So was Harry. Ron. We all were." She'd always been so proud of how smart she was, how good at everything. Never wondered why all of them managed to cast a Patronus so easily, or defeat wizards with twice their experience. The phrase _brightest witch of her age_ rose up to mock her. "We benefited from what they did!"

He groped for words that would comfort her. "Hermione, if the _Devoratrix Magicae_ had been closed the first time Voldemort was defeated, it is true that you would not have been the unwilling recipient of additional magical power. But had that happened, Voldemort surely would have opened the mouth again when he regained his body, in 1995. Who knows what dread plague would have spread across the globe? Would you have wanted millions dead, to salve your own conscience?"

"No, of course not." She turned away and went to the window to stare out at the swirling snow. "But to know that part of my magic wasn't meant to be mine," she said bitterly. "That it was stolen from someone else..."

He came to stand behind her, wondering what he could possibly say. "Molly and Arthur Weasley," he said at last. "Poppy Pomfrey. Kingsley Shacklebolt. Minerva McGonagall. Should they hate what they are?" 

She frowned, trying to understand his meaning, but he simply waited, knowing she would see it.

"Ah. They were all born during one of those times too, weren't they?" she asked quietly.

He nodded. "We cannot help what we are given, Hermione. What matters is what we do with it."

She pondered his words for a few moments. He was right: this wasn't a matter of personal responsibility. She bore no guilt for what had happened to her. His words shook her out of her own horror and sorrow, forcing her to think not about the past but the future. "Severus, we can't let this happen again. We have to destroy it."

To his relief, the haunted look had vanished from her face, replaced by determination. "We cannot be certain that no one will ever again stumble on knowledge of the Devourer," he said. "Knowledge can never be entirely erased; that is both its greatest virtue and its greatest weakness. But yes, we can at least destroy Salazar's, so that it cannot be used again. "

"You think it's hidden somewhere here, at Hogwarts." It was not a question but a statement. She knew it too.

He remembered a statue, a gaping mouth hungry for power. "Hidden, I think, in plain sight."

~~ Part 5: Endings and Beginnings ~~

"How are we going to explain this to Minerva?" Severus said, surveying the rubble that was once the statue of Salazar Slytherin.

Hermione pocketed her wand. "We'll just tell her we were doing our duty to our school. She ought to understand that."

"Her nostrils will flare."

"Probably."

A blank eye stared up at Severus from a chunk of stone, and he tipped it over with his boot. "And what of telling the rest of the world?" The tremendous reputation of Salazar Slytherin as Founder of Hogwarts, builder of the Chamber of Secrets, Master of the Basilisk, had always been a point of pride for Slytherin House. True, that reputation was marred by the fact that Salazar had turned it to evil uses, but how much worse to learn that it had all been built on stolen magic, and that he had made that same theft possible for others? 

"Surely young Slytherins are burdened enough," Hermione said, picking her way across the floor to his side. "They deserve to be judged on their own deeds, Severus, not the deeds of those who came before them. And you yourself have done everything you could to counter the aims of those who shared Salazar's obsession with blood purity." She tucked her arm into his and gave him a weary half-smile. "At least you know that your strength didn't deprive some other witch or wizard of their magical future. You were born in 1960."

"We all deserve to be judged on our own deeds," he said, reflecting her own words back to her. "And I have never heard that the _Devoratrix_ had any effect whatsoever on intelligence," he added, gently teasing. "Your reputation as the brightest witch of her age remains, I think, untarnished."

She nodded. It would take time, but she would come to terms with it. 

They stood in silence for a moment, then Severus spoke. "And now, perhaps you would like to join me for dinner? I have an idea for our next research project..."

**Author's Note:**

> Prompt: Hermione never stops asking questions. This time she questions something that nobody has ever dared to do: what is the nature of magic? Why are the students of Hogwarts taught to do things in a certain way? In her quest for answers, she discovers a dangerous and horrifying secret. And then she bumps into Severus Snape. An accident, or not? Will he aid her, or does he have a different agenda? (SS & HG.)


End file.
